The present invention relates to the general field of Radio Frequency Identification (RFID) transponder-reader systems, and more particularly to RFID-based management of physical assets that are located underground or within structures.
There are several technical problems associated with RFID-based management of physical assets which are located underground or within structures. An RFID transponder attached to the asset may be screened from the RFID reader/detector by intervening metallic covers, boxes, casings, etc., which shield and block RF transmissions. If the asset is deeply buried or embedded, the required read/write range may necessitate the use of more costly active and/or microwave RFID transponders. And if higher power RFID transponders are necessary, they can cause crossover interference among clustered assets.
The Access-Integrated RFID-Based Asset Management (AIRBAM) System addresses these problems by locating the RFID transponder in an RF-permeable means of access to the buried/embedded asset, rather than attached to the asset itself. This enables inspection/maintenance personnel to use a hand-held or portable RFID reader to retrieve information regarding the asset and its current status from the RFID transponder without opening the access structure.
Although the patent literature abounds with RFID-based asset management systems, none of these address the problems associated with remote and/or inaccessible assets.
While the US Patent of Duncan et al. (U.S. Pat. No. 7,002,461) discloses a RFID-based system for detecting hidden objects, such as manholes and anchor cables, it requires that the RFID transponders be attached directly to the objects. It does, however, make use of the optimal UHF frequency range of 902-928 MHz, which enables the use of low-power, relatively inexpensive tags with a range of several meters.
The US Patent Publication of Shinohara, et al. (2009/0009297) discloses a system for disclosing valve actuation information. Since the system requires that the RFID tag be affixed directly to the valve, it is not adaptable to remote or inaccessible installations. Moreover, the Shinohara system requires the use of active RFID tags, whereas an optimal system can employ either active or passive tags, depending on the range required.
The US Patent Publication of Krebs et al. (2009/0058610) describes a RFID-based system of valve detection. Although this document refers to the use of injection molding to embed the RFID transponder in plastic valve casings, the Krebs system cannot be modified to instead embed the transponder in the casing cover, since the system requires that the transponder be located adjacent to the reader within the valve casing.
The US Patent of Skorpik et al. (U.S. Pat. No. 7,791,480) teaches an RFID-based process control monitoring system, in which RFID sensor assemblies and cooperating RFID control tags are coupled or proximate to monitored components. While this system, like those previously discussed, is not useful in the context of remote and inaccessible components, it does employ the principle of a limited RFID read/write range in order to avoid crossover RF interference among clustered components, as does the present invention.